Sunday, July 11, 2010

Protein Intake for Pregnant Women

by Loren Cordain, Ph.D., Professor

Q: Hello Dr. Cordain

I would like to know if you could direct me to any research that indicates what amounts of protein are necessary for pregnant women who live the Paleo Diet way. I am in my third trimester with my first child and have been living Paleo since I first heard you lecture on it back at Boulderfest before your book came out. I have been the picture of health and my pregnancy has been very easy. I am finding that my protein and fat requirements are significantly higher.

Is there any research you could direct me to regarding protein requirements for pregnancy based on trimester?

Thank you very much and I look forward to hearing from you.

Best Regards,Lynda

A: Hi Lynda,

This question has come up before and the bottom line is that your probably should increase your fat and carbohydrate consumption, and limit protein to about 20-25% of energy, as higher protein intakes than this may prove to be deleterious to mother and fetus for a variety of physiological reasons. In my next book, I have devoted a chapter to maternal nutrition before, during and after pregnancy and why protein must be limited during pregnancy.

My colleague John Speth (an anthropologist) at the University of Michigan wrote a paper on protein aversion in hunter-gatherer women during pregnancy. Listed below is the abstract: (note the 25% protein energy ceiling!!!)

"During seasonal or inter-annual periods of food shortage and restricted total calorie intake, ethnographically and ethnohistorically documented human foragers, when possible, under-utilize foods that are high in protein, such as lean meat, in favour of foods with higher lipid or carbohydrate content. Nutritional studies suggest that one reason for this behaviour stems from the fact that pregnant women, particularly at times when their total calorie intake is marginal, may be constrained in the amount of energy they can safely derive from protein sources to levels below about 25% of total calories. Protein intakes above this threshold may affect pregnancy outcome through decreased mass at birth and increased perinatal morbidity and mortality. This paper briefly outlines the evidence for the existence of an upper safe limit to total protein intake in pregnancy, and then discusses several facets of the issue that remain poorly understood. The paper ends by raising two basic questions directed especially toward specialists in primate and human nutrition: is this protein threshold real and demographically significant in modern human foraging populations? If so, does an analogous threshold affect pregnant female chimpanzees? If the answer to both of these questions is yes, we can then begin to explore systematically the consequences such a threshold might have for the diet and behaviour of early hominids."2

The physiological basis for this aversion stems from a reduced rate of urea synthesis during pregnancy that is evident in early gestation1 as well as increases in the stress hormone cortisol3. Hence, pregnant women should include more carbohydrate and fat (i.e. fattier meats) in their diets and limit dietary protein to no more than 20-25% of their total caloric intake.

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